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Airtight, not uptight

Implementation of the latest revisions to the Building Regulations in England and Wales and Technical Handbook Section 6 to the Building Regulations in Scotland shows that the HVAC industry has played a part in shaping one particular change.

This could make a potentially significant contribution towards meeting the CO2 emissions reduction target.

Ductwork air-leakage is a factor in energy use and associated CO2 emissions, but until October this year SBEM (the core calculation tool for demonstrating compliance with the Building Regulations/Standards) was limited to calculating emissions on the basis of only Class A or B ductwork air-leakage. The effect of air-leakage on CO2 emissions could not be fully modelled.

Concise revision

However, the latest version has introduced two far more stringent ductwork air leakage classes: C & D, in accordance with the classifications outlined in BS EN 1507: 2006.

Research has shown that reducing air-leakage in ductwork systems has a direct impact on the energy needed to run the system.

Environmental Design Solutions (EDSL) used TAS 9.1.3a to model the annual effect of different ductwork air-leakage rates on four example buildings: two office blocks, a sports hall and a warehouse-sized retail unit.

It was found that in the offices and the sports hall, the increase in overall CO2 emissions was between 2.1 and 2.6 per cent.
In the context of the more demanding 2010 requirements, these figures could mean the difference between meeting or failing to meet its emissions target.

This relatively straightforward improvement doesn’t need to add significantly to costs.

Pre-insulated ductwork is capable of extremely high levels of airtightness and can readily meet the Class C or even Class D air-leakage limits.

Previously the benefits of this kind of system would not have been recognised in the compliance calculation, but with the new version of SBEM it can make a contribution towards the necessary carbon reduction.

As we approach zero-carbon building construction standards, the small details such as ductwork air-leakage will make it possible to meet th‑at standard.

Instead of being one of the last things to be considered, providing the option at design stage to include more efficient ductwork as part of the SBEM calculations gives specifiers greater flexibility and could potentially lead to reduced CO2 emissions and operational environmental impact.

John Garbutt is marketing director of Kingspan Insulation